Scroll forward to 2013 and I've now replaced a few of the first CFL bulbs with another new technology: mains power LED bulbs. I need to replace some of the older CFLs that had failed over the 8 or 9 years I'd had them and Tesco (of all people) had new 4W LED bulbs on special offer at around £8 per bulb. Now that's still a lot more than CFLs (which were being given away at one point and which you can quite happily get in pound shops these days). However I wanted to try them out as I have four down lighters in the kitchen that are used quite a bit and where I could really do with the crisper, bluer, more immediate light from the LEDs.
I thus spent £32 on replacing 4 x 14W CFLs with 4 x 4W LEDs (compared to 4x100W reflectors that were there when I moved in over a decade ago!). I liked the light and there's no "warming up" period (or at least none that I can detect). Whilst the LED bulbs were more expensive the energy savings of having them on for a few hours per day on a regular basis means that I should be financially in front after 5 years or so, and the LED bulbs have a much longer predicted lifespan.
With that good experience under my belt, I started to wonder if there were other bulbs I should consider replacing in my flat. The top contenders are the lounge standard lamp that is on for a few hours every evening, my bedside light (ditto) and the outside light above my front door (which could really do with a brighter light with no warm up whilst I'm trying to go up or down my iron staircase). As a result of discussions at the Footpaths Group at Loughborough University I started to wonder what the embodied energy of the various bulbs is and that's where things got alot more complicated.
Embodied energy is the energy required to actually make and distribute the product. The more complex the processing required to make a product and/or the more raw materials requiring high energy processing, the higher the embodied energy is. The US Government funded an analysis of the embodied energy in different types of bulbs:
- Incandescent bulbs require an average of 42MJ per 20 million lumen hours,
- CFLs require an average of 170MJ per 20 million lumen hours,
- Current LEDs require an average of 343MJ per 20 million lumen hours.